Plant atlas

Geographical Origin and Habitat: As the name suggests, Hygrophila guianensis is native to northern South America, particularly the Guiana region and the northern Amazon basin. In nature, it populates the muddy shores of slow-flowing rivers, marshes, and channels, growing mainly in emersed form during the dry season and completely submerged during floods. Its rustic nature allows it to tolerate temporary changes in water levels and strong seasonal currents.

Taxonomy & Genetics: Belongs to the Acanthaceae family. Within the genus Hygrophila, it is distinguished by the robustness of its stems and the significant size of its foliage. From a genetic point of view, it is an extremely robust plant that shares biological traits with other American Hygrophila species such as Hygrophila costata, showing a remarkable tolerance to pH and hardness fluctuations.

Physical Structure: It features thick vertical stems, woody at the base in more mature specimens, which grow erect and robust. The leaves are arranged oppositely, have an elongated, lanceolate shape, and can reach considerable size, up to 15-20 cm in nutrient-rich aquariums. The overall structure is imposing and massive, suitable for large aquariums.

Color & Texture: The coloration is a characteristic light green or pale apple green, very uniform and devoid of reddish hues even under strong light. This light green offers an exceptional color contrast when placed near dark or red-leaved plants. The leaf texture is smooth, soft but durable, with parallel secondary veins running towards the leaf margin.

Lighting & CO2: It is not a particularly demanding plant in terms of lighting, growing well even under moderate light. However, intense lighting promotes shorter internodes and more compact development. CO2 injection is optional but recommended to accelerate growth and stimulate the production of larger, fleshier leaves.

Nutrition & Substrate: Benefits from both a fertile substrate and regular liquid fertilization. As a medium-fast growing plant that produces a lot of biomass, it absorbs large amounts of nitrates, potassium, and iron directly from the

Water Chemistry: Tolerates soft to moderately hard water, with an ideal pH range between 6.0 and 7.5. The optimal water temperature is between 18°C and 28°C. Regular water changes help maintain nutrient balance and prevent organic accumulation that could encourage parasitic algae on older leaves.

Space Management & Placement: Its ideal placement is in the background of the aquarium or the rear part of the midground, due to its imposing size. It must be planted in individual stems spaced a few centimeters apart to allow light to reach the lowest leaves and prevent them from rotting prematurely.

Pruning: Pruning is done by cutting the upper part of the stem at the desired height. The plant responds by producing new lateral shoots from the node below the cut. Cut tops can be replanted directly in the substrate to propagate the species or thicken the decorative group.

Risks & Diseases: It is a robust plant with few associated risks. The main vulnerability is related to iron and potassium deficiencies, which manifest as leaf yellowing (chlorosis) or small holes. If allowed to grow out of the water, the emersed leaves will become darker and more leathery, and the plant may flower, producing small white or purplish flowers in the leaf axils.